The present invention relates to a process for the preparation of certain substituted 2-(dichloromethyl)pyridines and substituted 4-(dichloromethyl)pyridines.
Various substituted 2- and 4-(dichloromethyl)pyridines are taught, for example, in U.S. Pat. Nos. 4,172,203, 4,260,766, and 4,499,277, to be useful variously as herbicides, fungicides and insecticides. In addition, they are known to be intermediates for the preparation of herbicides, fungicides, insecticides, plant growth regulators, and nitrification inhibitors as disclosed, for example, in U.S. Pat. Nos. 3,173,919, 3,591,596, 3,838,159, and 4,497,652, and in U.S. patent application Ser. No. 653,399 filed Sept. 24, 1984.
Substituted 2- and 4-(dichloromethyl)pyridines have previously been prepared by a variety of methods, such as the reduction of the corresponding substituted (trichloromethyl)pyridines using a wide variety of reducing agents and the direct chlorination of substituted gamma and alpha picolines. In either case the ultimate starting material is a substituted gamma or alpha picoline. In view of the economic value of these compounds, it is desirable to have additional methods for their preparation which utilize other readily available starting materials.